Robotics are used in many industries, such as manufacturing, industrial applications, medical applications, and the like. Soft robotics is a developing area of robotics that provides soft, conformal, and adaptive graspers and actuators to enable robots to interact with objects in a similar manner to a human. In particular, such robots are able to manipulate objects in the same manner as a human hand. For example, if a part is on a shelf, a moving belt, or being moved from a shelf to a belt, an end effector may adapt to picking up the object from various directions, such as a “side pick” or a “top down pick.” This same grasper may also adapt to varying objects in each task, just as the human hand can.
A magnetic assembly to combine “hard” and “soft” robotics has been disclosed in A Hybrid Combining Hard and Soft Robotics, Stokes Adam A., Shepherd Robert F., Morin Stephen A., Ilievski Filip, and Whitesides George M., Soft Robotics. March 2014, 1(1): 70-74. doi:10.1089/soro.2013.0002, which article is incorporated herein by reference in its entirety. However, the proposed combination of hard and soft robotics does not provide the versatility necessary to operate similar to a human.
In particular, current end effectors have difficulty adapting to varying part location (e.g., on a shelf, on a conveyor belt, or the like). Additionally, current end effectors have difficulty adapting to varying part sizes and geometries. Still further, current end effectors need complex control systems to operate.
Furthermore, conventional soft robotic actuators are constructed from a single elastomeric material such as silicone elastomer. Some actuators incorporate elastomers of differing stiffness or wall thickness to accommodate a certain desired behavior. This layer of varying thickness or stiffness is sometimes referred to as a strain limiting layer. Some actuators use incorporated or coextruded fibrous materials in the elastomer body of the actuator itself. Such co-molded fibers are intended to improve resistance to puncture and strengthen the actuator. Some actuators use textile socks with slits to increase the operating pressure regime of an actuator.
However, all of these actuators have several limitations. In particular, actuators that use similar but stiffer elastomers to reinforce or restrain the actuator with thinned or thickened wall sections quickly become heavy and bulky because of the amount of excess material needed to achieve desired behaviors. This is because while stiffer, both materials are still elastomers of similar chemistries and can only achieve a very limited stiffness differential. In the case of silicones, whose stiffness is highly correlated with hardness, useful materials for soft actuators typically fall within the range of 10-80A Durometer yielding at most an 800% differential in stiffness between select regions of the actuator. This also means that when higher differentials in stiffness are achieved, it is mostly at the expense of strength in the weaker and softer elastomer regions.
Similarly, actuators that achieve higher function through reinforcement via thickened walls or slightly stiffer variants of elastomer are also limited to a select set of other equally important mechanical properties. As a result, these actuators can have poor mechanical damping characteristics, causing the actuator to appear floppy or poorly controlled. Additionally, such actuators can have limited resistance to tear or ablation compared to materials better suited to withstand puncture, acute damage, thermal shock, or general wear and fatigue. Furthermore, the load response of these construction materials is almost universally isotropic.
Actuators with fibrous reinforcements have been introduced by molding fibers into the actuator or co-extruded fibrous “pulp” as filler. Although such techniques provide slight improvements in puncture resistance and increased overall strength, this type of actuator precludes the possibility of modularity or repairs to such reinforcements without discarding the entire actuator. Additionally, fibrous reinforced actuators present a vulnerable rubbery surface to the environment, and issues of fiber delamination from the elastomer, limited fatigue life, and poor environmental resistance are prevalent.
The present disclosure is directed to the above limitations. In particular, the present disclosure provides improvements in interfacing hard and soft robotics and also provides improved actuators.